From 591c6d1710cd73824057d08eda302cf2a7cfd18a Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Thu, 8 Aug 2013 22:26:23 -0700
Subject: [PATCH] rcu: Flag lockless access to ->gp_flags with ACCESS_ONCE()
This commit applies ACCESS_ONCE() to an outside-of-lock access to
->gp_flags. Although it is hard to imagine any sane compiler messing
this particular case up, the documentation benefits are substantial.
Plus the definition of "sane compiler" grows ever looser.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 62b67b78b6611..6d028fdbf86ce 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1481,7 +1481,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
/* Handle grace-period start. */
for (;;) {
wait_event_interruptible(rsp->gp_wq,
- rsp->gp_flags &
+ ACCESS_ONCE(rsp->gp_flags) &
RCU_GP_FLAG_INIT);
if (rcu_gp_init(rsp))
break;